This invention relates to an impact type color printer.
As shown in FIG. 1, in a so-called impact type color printer, a platen 1 having a periphery provided with a plurality of members 2 saturated with different color inks and a printing head 3 having an impact means such as wires, are arranged opposite to each other with a printing paper 4 or any other material to be printed interposed therebetween, so that a selective one of the color inks is applied to the paper 4. The platen 1 is rotated by an electric motor (not shown) for color selection. The printing operation is carried out in such manner that the printing head 3 is moved one stroke together with the platen in parallel with a platen shaft 5 with a different speed, so that the printing head 3 may be progressively displaced with respect to the platen 1 in the axial direction thereof while the printing head 3 and the platen 1 are travelling along a line to be printed from one end to the opposite end of the line, so as to effectively and evenly utilize the axial printing range of an ink saturated member 2 of the platen 1. When the printing head 3 reaches the last end of the line, the printing paper 4 is transported in the direction of the arrow U to change the line, so that a new line may come to the position opposite to the head 3. However, if a relative position between the platen 1 and the printing head 3 is maintained always constant, the ink saturated member 2 will be partially consumed or worn out, and the print becomes inproper.
This may be avoided by rotating the platen 1 a little within the same member 2 with respect to the printing head 3 each time the line is changed, so that the same ink saturated member 2 will be subjected to impact by the printing head 3 in a different axial range thereof.
Nevertheless, there still remains another problem. More particularly, the partial ink consumption and abrasion of the ink saturated member 2 will also be caused if the initial angular position of the platen 1 is always predetermined with respect to the printing head 3 each time the printer is turned on for printing operation. Now, this problem remains to be solved.